Hi again,
Original message below
I have changed the O2 sensor and the problem persists.
With sensor disconnected the van accelerates smoothly, with the sensor
connected the van hesitates.  With O2 sensor hooked up the volt meter is
showing 0 to "negative" 0.05 volts for about 3 to 4 seconds during
acceleration.  Another observation: during deceleration above 1250 rpm
fuel is being cut off to the injectors (with O2 sensor disconnected from
computer and the volt meter hooked up to the O2 sensor) the volt meter
reads "negative" 0.05 volts if I engage the A/C compressor the voltage
then goes to "negative" 0.1 volts.  Could this be due to bad ground?

Help me please!

Kai
87.2 Westy

Hello All,
Went through the Digifant/Bosch system and came up with a O2 sensor
question.  With O2 sensor unhooked from the computer the engine will
accelerate fine under load (AC compressor on).With the sensor hooked up
the engine has severe hesitation.  One would think: exchange the O2
sensor and get on with your life, but here's the kicker.  With the volt
meter hooked up to the now back inline O2 sensor I'm getting readings
which to my knowledge are correct.  In idle the volt meter bounces back
and forth between 0 and 0.6 volt.  During acceleration under load (A/C
compressor on) the volt meter then drops to "negative" 0.1 volts for
about 3 to 4 seconds which is approximately the same duration of the
hesitation. Indicating a lean mixture.

Question #1: Isn't this exactly what the O2 sensor is supposed to do?
Question #2: Why is the computer not compensating for this voltage drop?
Question #3: Why am I getting "negative" 0.1 volts for about 3 to 4
seconds? (using analog gauge need to switch polarity to measure negative
volts)
Question #4: Will a new O2 sensor fix this problem?

Additional data if needed, compression check #1: 150, #2: 175,#3: 135,
#4: 165.  Vacuum test (intake manifold) at idle 14.5 in. at 1500 rpm 17.5
in., at 2000 and up 20in. Hg (Live in Florida elevation 0) 135000 Miles

Any help is highly appreciated, Thank You

Kai  87.2 Westy

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